If the house is passed on to a child, they are forced to sell whether they can afford the taxes or not because now they have decades of built of tax debt they need to pay off out of the estate. If you defer until sale and the elderly person sells when they can't take care of themselves anymore, they have less money with which they can get a new residence.
Sure, I wasn't suggesting that a special tax break created for elderly who wish to avoid moving out of a house they were fortunate enough to buy for far less than its current market value should continue to apply when they no longer need the house.
Why wouldn't you organise things so that property-owning dynasties aren't able to freeload off the appreciation in their property values accruing from the work and taxes paid by others?